Full Idea
If a number of human beings were born adult, and only a few here and there were born infants, everyone would pity the infants, because we should then consider infancy not as a thing natural and necessary, but as a defect or fault of nature.
Gist of Idea
If infancy in humans was very rare, we would consider it a pitiful natural defect
Source
Baruch de Spinoza (The Ethics [1675], V Pr 06)
Book Reference
Spinoza,Benedict de: 'Ethics', ed/tr. White,WH/Stirling,AH [Wordsworth 2001], p.233
A Reaction
A lovely example of the new objectivity about human beings that emerged in the Enlightenment. He could have said the same about old age.